Nauka ta progres transportu (Oct 2014)
INFLUENCE OF CHEMICAL COMPOUNDS ON THE FORMING OF WELDING ARC
Abstract
Purpose. The purpose of work is a comparative analysis of chemical compounds influence on the process of forming arc welding and condition of its burning. Methodology. A wire with diameter 3 mm of low carbon steel with contain of carbon 0.15% was material for electrode. As chemical compounds, which determine the terms of arc welding forming the following compounds were used: kaolin; CaCO3 with admixtures of gypsum up to 60%; SiO2 and Fe − Si with the iron concentration up to 50%. Researches were conducted using the direct electric current and arc of reverse polarity. As a source of electric current a welding transformer of type PSO-500n was used. On the special stand initial gap between the electrode and metal plate was 1-1.5 mm. The inter electrode space was filled with the probed chemical compound and the electric arc was formed. At the moment of arc forming the values of electric current and arc voltage were determined. After the natural break of electric arc, the final gap value between electrodes was accepted as a maximal value of arc length. Findings. Experimentally the transfer of metal in interelectrode space corresponded to the tiny drop mechanism. According to external signs the relation between maximal arc length and the power of electric current has the form of exponential dependence. Specific power of electric arc at the moment of arc forming per unit of its length characterizes the environment in the interelectrode space. Originality. 1) Based on the analysis of influence of the studied chemical compounds on the formation processes of electric arc the inversely proportional relationship between the power of the electric current and the maximum arc length until the moment of its natural break is defined. 2) Ratio between the maximal arc length and the power of electric current, with the sufficiently high coefficient of correlation is submitted to the exponential dependence. Influence of the compounds under study on the process of electric arc forming is determined using the indexes of degree of the above mentioned correlation. 3) The value of specific power of electric current at the moment of electric arc forming per unit of arc length can be accepted as the parameter, which characterizes the state of interelectrode space environment. Practical value. In the conditions of identical adjusting force of electric current the sequence of location of the studied compounds in the order of increase of their influence on the process of arcing is determined. Minimum influence is observed from kaolin, and maximal one – from Fe − Si .
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